In recent decades, the use of synthetic fibers due to the high quality, durability and price has gained momentum due to their application as pile in machinery carpet. The mechanical properties such as bending rigidity and resilience of carpet pile are the most important factors in maintaining the appearance of the carpet. Polyester fibers suffer from lower bending rigidity and resilience properties in comparison with acrylic and nylon fibers and hence wealth of research works has done to improve or modify the mechanical properties of polyester multi-filament. In this research, the effect of various parameters of the melt spinning process and air texturizing on the physical properties of polyester yarns with application in carpet pile was investigated. Using Tagochi model, design tests for survey parameters including extrusion temperature, filament fineness and quench condition in the process of melt spinning, as well as primary and secondary godets temperature, draw ratio between godets and heater temperature in the process of air texturizing, was carried out on three levels and 27 air texturized yarns were produced. Then using the yarn tensile tests in direct and knot modes, the knot efficiency and difference between strength in direct and knot modes was calculated, and two samples with the highest and one sample with the lowest bending rigidity was selected. In the next stage, three samples were produced and compressive loading test and short time static loading was done on the samples. Afterwards, percentage of lost thickness, compression and resiliency of carpet pile was calculated. Analysis of result was done using a one-way analysis of variance (ANOVA). It was found that larger difference between the strength of yarn in direct and knot modes results in higher bending rigidity which indicates the effect of filament fineness on bending rigidity and rapture mechanism of the knot. It was also established that larger difference between the strength of yarn in direct and knot modes results in higher yarn resiliency indicating the effect of yarn structure on carpet pile resilience. It was also found that higher knot efficiency results in lower resilience and bending rigidity which indicates the accuracy of performed analysis on the impact of the bending rigidity on rapture mechanism of knot. Key words : bending rigidity, carpet pile, knot efficiency, resiliency, Tagochi method, air texturizing